A large animal such as a horse has a good deal of body mass. An average size horse can weigh over 1400 lbs. Under normal conditions a horse does not require external assistance with thermoregulation. However, in instances of extremely hot and or humid environmental conditions, great physical exertion, and during illness, horses and other quadrupeds can generate a lot of extra body heat that can become life threatening if not properly managed. Hyperthermia, also known as heat stroke is a dangerous condition whereby a horse is unable to lose body heat, and its body temperature goes up rapidly causing severe health concerns that can result in an unsafe drop in blood sugar, colic, muscular denaturation (cooking), renal failure and or fatality. Consequently, untreated excessive heat has a destructive effect on the cells of all equine tissue, and is particularly important with regards to the brain. In the case of a domestic large animal like the horse, it is the responsibility of the caretaker to ensure the safety and wellbeing of the animal through the best means available, sometimes under less than optimal circumstances. The goal is to safely cool the horse. Successful heat removal can be accomplished by methods of radiation, convection, evaporation, and conduction with some techniques being more effective than others when dealing with horses.
Original evaporative cooling interventions include dousing an overheated horse repeatedly with buckets of ice water spread over their back, neck and legs, and using a tool to serve as a scraper to rapidly wipe away the water from the surface area of the horse as the water becomes heated. Unfortunately the water applied under this method heats up almost instantaneously, and therefore requires rapid scraping followed by the application of more iced water. This sequence continues until there is a change in in the horse's core temperature. This protocol serves as a cumbersome challenge since above and beyond the person-power involved, having enough ice readily available to significantly cool the water takes planning, not to mention that even with access to ice, enough water is not always easily available and or transportable on long rides away from home, during hauling in a hot trailer, shipping by airplane, with unforeseen illness, or at the competition arena with a post-competition horse wearing full tack, or equestrian gear.
Convective heat loss used for equine cooling, is accomplished through the movement of air around a horse that is of a lesser temperature than the core temperate of the horse. However, as the air temperature circulating around the horse becomes close to its body temperature, actual heat loss due to convection rapidly declines until the ambient temperature equals the horse body temperature and convection heat loss ceases. Additionally, the electricity necessary for some standard, prior art cooling devices such as a conventional fan, portable air conditioner, or water misting machine makes things equally difficult when a horse unexpectedly presents as hyperthermic in a rural environment, or while in transit void of utilities, or in the show ring where a natural breeze is not to be relied upon and fans are seldom provided.
Prior art Russakoff and Campbell, U.S. Pat. No. 9,386,759, Jul. 12, 2016 discloses a towel with an elaborate fastening system for the management of heat stress that fits over a large animal such as a horse. According to detailed description, this art requires vigorous, and periodic flapping to continually ensure support of its evaporative nature. Regardless of which portion of the horse the disclosed towel covers, the requirement of flapping by design is inconvenient at best and at worst, a dangerous necessity when dealing with a hot, very large prey animal with an instinctual fight or flight defense mechanism. The need to vigorously wave an article of fabric manually or artificially, that is attached with a buckle assembly to an already compromised 1400 lb animal is dicey and puts the caretaker at risk of injury if the horse attempts to flee, as well as further stresses the animal by raising its anxiety with the compulsory fabric agitation. Alternatively, using a fan and therefore needing the necessary electricity (or gas and generator) to run a piece of equipment to assist with vigorous flapping makes this towel as inconvenient as the above mentioned, original interventions. Lastly, this prior art of evaporative cooling will not fare well when the relative humidity is high outside. When the ambient water vapor pressure approaches that of the moist surface of the towel/skin evaporation is impeded.
What is needed is an invention that solves the requirement of effectively cooling a large animal like a horse after exercise, travel and or during fever from illness, while overcoming the aforementioned disadvantages of constant movement, electricity, water, ice, extra person-power and cumbersome devices.
Separate from heat stress, is the issue of sickness and the associated hurdles a caretaker must overcome to effectively reduce the core temperature of an ill animal. The horse is an exceptionally designed, athletic animal that must keep their brain cool during exertion and illness. Typically, the normal rectal temperature for a healthy, adult horse is between the range of 99.5-101 degrees Fahrenheit, with alert, active and responsive reactions to noise and visual stimuli, good appetite and ample fluid intake. However, while sick or injured, a horse's temperature can elevate well past the high end of the normal range of rectal temperatures to as high as 107 degrees Fahrenheit.
Symptoms of a febrile horse include a general malaise and lethargy, loss of appetite, reduction of water intake, decrease in urine and manure output and a reduction or absence of normal gut sounds associated with healthy intestinal movement and digestive functions, which are key components to a well horse. Horses, unlike other quadrupeds are non-emetic, and therefore cannot throw-up when sick. As a naturally grazing species, the sensitive digestive tract of horses is designed for and requires constant grazing. Severe complications for a horse can arise in connection with a fever that lasts for more than a couple of days, when the impact of the fever creates a loss of appetite, a decrease in consumption, and or dehydration.
Traditional treatment and prior art for high equine fevers over 104 degrees Fahrenheit due to illness, include pharmacological intervention such as non-steroidal anti-inflammatory drugs, and a cold bath with thorough and continual scraping to remove the warmed excess water. Unfortunately, prior art solutions involving the use of person-power for scraping cold water is cumbersome and exhaustive as stated above, not to mention not always accessible or effective when used by itself. The use of antipyretic medication for the treatment of fever has potentially undesirable consequences for the horse such as gastrointestinal ulcers and renal complications. Regardless, as will be addressed, there are times when drugs do not work to reduce a fever.
Jonathan Naylor, BVSc, PHD, Dipl. ACVIM and Keith Baptiste BUMS, MSc, PhD, DACVIM both theorized and successfully tested their hypotheses, that there was more to equine thermoregulation that involved the equine guttural pouches. The guttural pouches are bilateral, fist-sized cavities located in the horse's skull, which sit slightly behind the ears. Each guttural pouch contains 300-500 ml of air and functions autonomically during selective brain cooling. Accordingly, Drs. Baptiste and Naylor believed that respiratory and circulatory functions of a healthy horse naturally serve to maintain cooler air in the guttural pouches, thus cooling the blood supply carried within the vascular network associated around and within the guttural pouches, ultimately leading to the brain working to achieve a cooler core temperature.
Extensive testing by Naylor and Baptiste discovered that in heavily exercised, otherwise healthy horses, (meaning horses that engaged in cantering at between 10-17 miles per hour for five uninterrupted minutes, the blood leaving the guttural pouches was an average of three degrees Fahrenheit cooler than the blood that arrived at the location where the vascular system entered the guttural pouch. This was a drop from 103.1 degrees Fahrenheit to 100.04 degrees Fahrenheit. Although a significant finding, a post-exercise, healthy equine temperature of 103.1 degrees Fahrenheit is not as alarming as the core temperature of a sick horse reaching 107 degrees Fahrenheit during heat stroke or illness. As such, an invention that helps cool a hot horse without disadvantages is needed.